Hand, Foot and Mouth- How long contagious?

Hi,
My DD and DS both have hand, foot and mouth. I was just wondering if anyone knew if it was no longer contagious once scabbed over (similar to chickenpox).
It's just that this has spread so fast, my neice caught it from her little friend who got it from someone at nursery. But in the meantime before her blisters had come up she had already been in contact with another little friend, my DD and my other neice.
Then we had been mixing with other children and a few days later DD blisters came up. Yesterday DS blisters broke out. Feeling pretty housebound but worried it just seems to catch with the smallest contact.

Hand foot and mouth is contagious roughly for a few days before the symptoms appear untill they start to feel better and the spots and ulcers have healed over ( so usually about 7 to 10 days after it starts).